1. Field of the Invention
The disclosed embodiments relate to medical devices. More specifically, the disclosed embodiments relate to catheters that are inserted into blood vessels or the like.
2. Description of Related Art
A catheter that is inserted into a tubular organ, such as a blood vessel, an alimentary canal, or a ureter, or an internal bodily tissue, structurally includes an inner layer (base tube) made of a resin, an outer layer surrounding the outer periphery of the inner layer and made of a resin, and a braid (reinforcement layer) interposed between the inner layer and the outer layer. This braid is formed by weaving wires made of a metal such as copper or stainless steel together in consideration of properties required for a catheter, such as pushability, torque transfer capability, and pressure resistance. For example, a braid is known in which first wires made of stainless steel and second wires made of stainless steel are wound such that the first wires form left-handed helices and the second wires form right-handed helices (see Japanese Patent No. 3184086).
In order to prevent woven first wires and second wires from being detached from one another, a braid has been developed in which first wires and second wires are welded or joined together by an adhesive or the like at intersection points at which the first wires and the second wires cross one another (see U.S. Pat. No. 6,562,022, for example). A braid has also been developed in which first wires and second wires are welded by a laser beam at intersection points at which the first wires and the second wires cross one another (see Japanese Unexamined Patent Application Publication No. 2005-230318, for example).
However, with the above described method of joining the first wires and the second wires together at the intersection points, it is difficult to join the first wires and the second wires together with high joint strength. Specifically, a thin braid is required for size reduction of a catheter body. If, however, the thicknesses of first wires and second wires of the braid are reduced for this purpose, a necessary joint strength between the first wires and the second wires is not sufficiently secured by only joining the first wires and the second wires together at the intersection points. If, for securing a necessary joint strength, the first wires and the second wires are joined together by using another member such as a clip or an adhesive, the object of reducing the thickness of the braid will not be achieved.
If, on the other hand, the material used for first wires differs from the material used for second wires, it may be difficult to weld the first wires and the second wires together by a laser beam. In this case, the only method of joining the first wires and the second wires together is to use another member such as a clip or an adhesive, and thus the object of reducing the thickness of the braid will not be achieved.